螺纹底孔直径尺寸表M1:粗扣螺距 0.25 = 0 0.75M2:粗扣螺距0.4 = 0 1.6M3:粗扣螺距0.5 = 0 2.5M4:粗扣螺距0.7 = 0 3.3M5:粗扣螺距0.8 = 0 4.2M6 :粗扣螺距1 = 0 5M8 :粗扣螺距1.25 = 0 6.7M10:粗扣螺距1.5 = 0 8.5细扣螺距0.2 = 0 0.8细扣螺距0.25 = 0 1.8细扣螺距0.35 = 0 2.7细扣螺距0.5 = 0 3.5细扣螺距0.5 = 0 4.5细扣螺距0.75 = 0 5.2细扣螺距 1,0.75 = 0 7,0 7.2细扣螺距 1.25,1,0.75 = 0 8.7,0 9,0 9.2M12:粗扣螺距 1.75 = 0 10.2细扣螺距 1.5,1.25,1 = 0 10.5, 0 10.7, 0 11M14:粗扣螺距2 = 0 11.9M16:粗扣螺距2 = 0 13.9细扣螺距 1.5,1 = 0 14.5,0 15M18:粗扣螺距 2.5 = 0 15.4细扣螺距 2,1.5,1 = 0 15.9, 0 16.5, 0 17M20:粗扣螺距 2.5 = 0 17.4细扣螺距 2,1.5,1 = 0 17.9, 0 18.5, 0 19M22:粗扣螺距 2.5 = 0 19.5细扣螺距 2,1.5,1 = 0 19.9,0 20.5,0 21M24:粗扣螺距3 = 0 20.9细扣螺距 2,1.5,1 = 0 21.9,0 22.5,0 23M27:粗扣螺距3 = 0 23.9细扣螺距 2,1.5,1 = 0 24.9, 0 25.5,0 26M30:粗扣螺距 3.5 = 0 26.3M33:粗扣螺距 3.5 = 0 29.3细扣螺距 3,2,1.5, =0 29.9, 0 30.9, 0 31.5M36:粗扣螺距4 = 0 31.8细扣螺距 3,2,1.5, =0 32.9, 0 33.9, 0 34.5M39:粗扣螺距4 = 0 34.8细扣螺距 3,2,1.5, =0 35.9, 0 36.9, 0 37.5M42:粗扣螺距 4.5 = 0 37.3细扣螺距 4,3,2,1.5, =0 37.8, 0 38.9, 0 39.9, 0 40.5M45:粗扣螺距 4.5 = 0 40.3细扣螺距 4,3,2,1.5, =0 40.8, 0 41.9, 0 42.9, 0 43.5M48:粗扣螺距5 = 0 42.7细扣螺距 4,3,2,1.5, =0 43.8, 0 44.9, 0 45.9, 0 46.5M52:粗扣螺距5 = 0 46.7螺纹底孔直径尺寸表.txt生产中钻螺纹底孔公式：t 1mm: Dz=d-（1.041.06）t式中t螺距（毫米）Dz攻丝前钻头直径（毫米）d螺纹公称直径（毫米）生产中钢料可按数值选取，软料钻头直径可选大些，但不可太大